Contact glasses in ophthalmic surgery are examples of adapters which mechanically couple the laser processing device to an object. Such coupling is required because the precision with which the laser beam is positioned in the object usually determines the precision achieved in processing. Only exact three-dimensional positioning of the laser beam in the processing volume, for example in the cornea of the eye, allows high-precision processing. Therefore, fixation of the object to be processed is effected via an adapter ensuring a precisely defined position of the object, for example of the eye, relative to the laser processing device. The adapter, which is usually referred to as contact glass, is thus part of the beam path. If the exact external shape of the object to be processed is not known, the adapter at least also functions to give the object, if possible, a certain shape which is pre-defined when applying a laser beam.
Since the anterior surface of the human eye's cornea varies from patient to patient, an adapter in the form of a contact glass is regularly provided in laser-assisted ophthalmic surgery. US 2001/0021844 A1 describes a corresponding contact glass which not only fixes the eye, but also deforms the anterior surface of the cornea. The US publication proposes to apply a vacuum between the cornea and the contact glass provided as a lens body, by which vacuum the eye's cornea is drawn towards the contact glass. With the lens body and the eye's cornea fixed by vacuum in this manner, the eye's cornea automatically assumes the shape of the lens body's anterior surface (anterior surface with respect to the patient). However, this type of fixing is rather inconvenient for the patient, in particular when using the barb-shaped projections provided at the bottom surface of the lens body mount according to one embodiment of US 2001/0021844 A1, said projections being intended to achieve improved fixing of the contact glass to the eye.